Pool Gallon Calculator
Pick your pool shape and enter dimensions to get how many gallons your pool holds.
What your result means
This is the pool's volume in gallons, at 7.48 gallons a cubic foot. It's the figure for chemical dosing and for estimating your fill cost, since city water is billed per 1,000 gallons. A garden hose runs 5 to 15 gallons a minute, so a big pool takes a while to fill.
How to use this calculator
- Pick shape and enter dimensions.
- Read gallons.
- Use for chemical dosing and water bill estimation.
- Initial fill: divide by water meter unit (cubic feet, gallons).
- Re-test water level weekly.
The formula
Find the volume in cubic feet from the shape area times average depth, then multiply by 7.48 for gallons.
Worked example
Say you've got a 30 by 15 ft rectangular pool at 5 ft average depth. That's 16,831 gallons.
Fill cost & time
| Item | Value |
|---|---|
| 1 cubic foot | 7.48 gallons |
| Garden hose flow | 5 – 15 GPM |
| Fill cost (15,000 gal) | $40 – $150 |
Tips & gotchas
- One cubic foot is 7.48 gallons.
- Always dose chemicals by gallons.
- City water is usually billed per 1,000 gallons.
- An initial fill can be $50 to $200 in water alone.
- Use a water-source meter to track the exact fill.
Frequently asked questions
How many gallons is my pool?
Use the calculator with your dimensions.
How much does it cost to fill a pool?
A 15,000 gallon pool is $40 to $150 in water, depending on local rates.
How long does it take to fill a pool?
A garden hose runs 5 to 15 GPM, so a 15,000 gallon pool is 17 to 50 hours.
Does pool gallons matter for liner sizing?
No. A liner matches the dimensions, not the gallons.
How do I figure gallons for an oval pool?
Use the Oval shape. Length is the longer dimension, width the shorter.
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